The present invention relates to an electric regulator unit for regulating various quantities of state in instruments such as an air conditioner for automotive vehicles, a car stereo player and the like.
Conventionally, there is known an electric regulator unit shown in FIGS. 1 and 2 of the accompanying drawings. The known electric regulator unit, generally designated by the reference numeral 1, comprises a holder 2 which is arranged wthin a body frame of an instrument such as an air conditioner (not shown) or the like. The holder 2 is mounted to one of a pair of mount plates of the body frame against rotation relative thereto. The holder 2 has a cylindrical outer peripheral surface and has one axial end face formed therein with a recess. A variable electric component 3 such as a variable resistor, a variable capacitor or the like has a body and an operating shaft 3a supported by the body for angular movement relative thereto about an axis of the operating shaft 3a. The body of the variable electric component 3 is accommodated in the recess in the holder 2 such that an axis of the operating shaft 3a of the variable electric component 3 coincides with a central axis of the holder 2. A knob 4 has a cylindrical outer peripheral surface 4b and has one axial end face formed therein with a recess. An assembly of the holder 2 and the variable electric component 3 is accommodated in the recess in the knob 4 such that the axis of the operating shaft 3a coincides with an axis of the knob 4. The knob 4 is mounted to the other of the above-mentioned pair of mount plates for angular movement relative thereto about the axis of the operating shaft 3a.
The operating shaft 3a of the variable electric component 3 has an end portion formed with a pair of diametrically opposed planar surface sections. The end portion of the operating shaft 3a is fitted in a central bore 4a which is formed in a bottom of the recess in the knob 4 and which is complementary in cross-sectional shape to the end portion of the operating shaft 3a, so that the operating shaft 3a of the variable electric component 3 is movable together with the knob 4 angularly about the axis of the operating shaft 3a. The variable electric component 3 is provided with a plurality of terminals 3b which extend through a through bore 2a formed in the bottom of the recess in the holder 2. Forward ends of the respective terminals 3b are exposed to the outside, whereby lead wires can be connected to the forward ends of the respective terminals 3b by means of soldering or the like.
The cylindrical outer peripheral surface 4b of the knob 4 is formed with irregularities by means of knurling or the like so that the outer peripheral surface 4b is given high friction resistance in order to facilitate manipulation of the knob 4. A part of the outer peripheral surface 4b is exposed to the outside through a window 5a formed in an operating panel 5, as shown in FIG. 2.
The holder 2 is provided on its one axial end face with a projection 2b. On the other hand, an arcuate projection 4c is formed on the bottom of the recess in the knob 4 and extends along the peripheral wall surface of the recess. When the knob 4 is moved angularly about the axis of the operating shaft 3a relatively to the holder 2 and the body of the variable electric component 3, either one of the opposite ends 4d and 4e of the arcuate projection 4c can be abutted against the projection 2b on the holder 2, thereby limiting the angular movement of the knob 4.
In use of the electric regulator unit 1 constructed as above, an operator manipulates, with this finger, the part of the outer peripheral surface 4b of the knob 4, which is exposed to the outside through the opening 5a in the operating panel 5, in the direction indicated by X in FIG. 2. The operator's manipulation moves the knob 4 angularly about the axis of the operating shaft 3a of the variable electric component 3. The angular movement of the knob 4 is transmitted to the operating shaft 3a through the engagement between the bore 4a in the knob 4 and the end portion of the operating shaft 3a. Thus, the operating shaft 3a is moved angularly about its axis, whereby the variable electric component 3 can be set or adjusted to any desired resistance or capacitance value.
However, the electric regulator unit constructed as described above has the following problems. That is, since the diameter of the cylindrical outer peripheral surface 4b of the knob 4 is relatively large, only an extremely small manipulating force is required for angularly moving the knob 4. Threfore, an inadvertent light touch on the outer peripheral surface 4b of the knob 4 causes the operating shaft 3a of the variable electric component 3 to be moved angularly so that the electric value of the variable electric component 3 is deviated from the set desired value unintentionally.